The present invention relates to vehicle braking systems.
Brake systems incorporating anti-lock braking systems (ABS) and the related traction control brake intervention systems (TC), are conventionally used. ABS is achieved by providing a mechanism for rapidly releasing pressure at a selected wheel brake when incipient wheel slip occurs during vehicle braking. A mechanism for re-applying braking pressure as needed during ABS cycling is also typical. TC is achieved by providing a mechanism for applying braking pressure at a selected heel brake when incipient wheel slip occurs, generally during various forms of vehicle acceleration.
ABS and TC systems generally incorporate a pressure gradient generation mechanism such as a pump to automatically provide appropriate braking pressure apply and release rates. The pump must be capable of effecting rapid pressure changes at the wheel brake and therefore, its fluid flow capacity capabilities are critical. The internal leakage inherent in fluid flow control mechanisms typically used for braking systems increases the capacity that must be designed into the pump. This contributes to system complexity, inefficiency and cost. Accordingly, a more efficient braking system is preferable.